US2332054A - Engine starter drive - Google Patents

Description

OGL 19, 1943. 1 E BUXTCSN 2,332,054

ENGINE STARTER DRIVE Filed Dec. 9, 1941 Patented Oct. 19, 1943 *UNITE D STATE-'S FF! CFE 2,332,054 ENGINE STARTER DRIV-E IamesE. fl'uxtomfElmira, N. Y., assigner to' Bendix Aviation Corporation, lSouth Bend, Ind., a corporation of Delaware 'Application December 9, 1941, Serial No. 422,241

v,2 claims.

'che present invention relates to an engine -In those forms 'of starter drive 'in which a 'pinion fis projected by a threaded connection into mesh with an engine geanwh'en the starting mo- `to`r is "accelerated, some form of yielding connection is necessary. The utilization of many forms The power sha-ft 'I is provided' withl a further reduced extension 6 on which a screw shaft 'I is fiiied as by means of apin 8. Screw shaft 'l is provided with a smooth portion 9 and a threaded portion lll of lthe samev external tdiameter as the smooth portion 2 of the power shaft.

y 'Means for traversing and rotating the pinion 4 from the screw Vshaft is provided comprising a nut 'member SI2 normally journalled on the ofrubber-like substances'to perform this function 'i0 srr'iootl'l portion 9 of 'the screw Shaft and urged yby virtue of their elastic resistance to deformainto initial engagement with the threads Il by tion have been pro-posed, some forms tilizing the `'means of a re-er'ltryspring vI3 which bears at elasticsubstance'in compressionjsome in torsion, one end against athiinble Ill anchored on the and some in both compressionand torsion; and screw vshaft by 'a lock wire 15, Land Tat 'the other each form vhas been `found to have certain adl5 end against `a thim'ble i6 slidably mounted on vantages and limitations for specic uses. the screwshaft. n A flange Il on the screw shaft It is an object of the present'invention'to prolimits the sliding movement 'of the thimble IG vide la novel yielding drive for engine starters `so as to denne `the idle position of the nut v.i2 `which is eiiicient and reliable in operation'and in initial engagementwith 'the end 'of 'the threads economical in construction; H. v f

-'I-t is 'another object to provide such a device Nut -I2 is provided with aradialange l!! havwhich `is of large torque capacity in proportion ing-a splined connection as `indicated at i9 With 'to the volume oi its cushioning element. a barrel member 2i fixed to the pinion 4 at 22. It is another object `to provide 'suena-device A Alock ring v23 is provided for `retaining the nut in which the yielding connection comprises a i2 within the barrel 2l. According tothe presrubber-like member which'is placed-in axial shear ent invention an elastically 4deformable annular "whenthe drive is torqu'ed. y'member 2li is mounted in the barrel 2|, seated Itis a vfurther object to provide such a device on the nut I2, land so connected interiorly and -incorporating -means for vrelieving 'the yielding exteriorly to the nutand barrel respectively, that member from the application vof torque thereto. relative movement between the nut and barrel lIt is another object 4to provide such a device places the elastic member in ar'ialshear. As here yin which the engagement of the `pinion Withvthe shown, this is accomplished by 'bonding sleeves engine vgear is cushioned and facilitatedv bythe 2'5 .and 26 t0 the interior and exterior of the anyielding'action of the rubber-likefrn'embe'r in axial "nul'ar member 24, theinterior sleeve 25 being in shear. v fabiitting relation-'with the a'nge I8 of vthe nut, liir'ther objects'and advantages will be appar- 'and thefs'l'eeve 25 "being-'seated against a shoulder ent from the following description taken in cony2'! formed in the interior 'of the barrel 21. In nection with the accompanying drawing, in this form of the invention the member 24 is which: shown as having a conical or truncated form so Fig. 1 is a side elevation partly in section of 40 arranged that when shearing stresses are apa starter drive incorporating a preferred emplied thereto during the operation of the drive, bodiment of the present invention; the member tends to be flattened out.

Fig. 2 is a similar View of a second embodiment In the operation of this embodiment of the inof the invention; vention, rotation of the power shaft I is trans- Fig. 3 is a detail in perspective of the yielding 45 mitted through the pin 8 to the lscrew shaft 9. driving member shown in Fig. 2; and The nut I2 is thereby threaded along the screw Fig. 4 is a view similar to Fig. l of a third shaft 9, moving the barrel 2| and piniondA ahead embodiment of the invention. of it by means of the yielding member 24 until In Fig. 1 of the drawing there is illustrated a the pinion 4 meshes the engine gear 5 and enpower shaft l having a smooth reduced eXtengages the abutment shoulder 3. Thereafter furson 2 providing a thrust shoulder 3 A pinion ther longitudinal movement of the nut IZ places 4 is slidably journalled on the smooth portion 2 themember 24 in axial shear until the elastic of the shaft for movement into and out of enresistance to this shearing movement-l causes sufgagement with a member such as a gear 5 of cient torque to be transmitted through splined an engine to be started. connection I9 between the nut and barrel to cause rotation of the pinion to crank the engine. When the engine starts, the overrunning of the engine gear returns the parts to idle position.

In the embodiment illustrated in Fig. 2, the arrangement is substantially similar to that shown in Fig. 1 except that the annular elastic member is normally fiat, and the axial shearing forces engendered by the transmission of torque deform the member into a truncated shape. The nut l2 is provided with an abutment shoulder I0 for spacing the sleeve 25 from the ange I8 in order to permit this telescoping movement of the parts. In this form also, the step 2 of the power shaft I is removed in order to permit the use of a smaller drive pinion 4. y

The operation of this embodiment of the invention is substantially the same as above set forth.

In Fig. 4 there is illustrated a power shaft 3l having a smooth reduced portion 32 providing a stop shoulder 33 and a splined portion 34. A screw shaft 35 is slidably keyed on the splined portion 34 of the power shaft, normally abutting against a ring 36 pressed on the splined portion 34 of the shaft until stopped by the run-out 3l of the splines.

Screw shaft 35 is provided with a threaded portion 38 and a smooth portion 39 on which is normally mounted a nut member 4I having a radial flange 42. A pinion 43 is slidably journalled on the smooth portion 32 of the power shaft for movement into engagement with an engine gear 44. A barrel member 45 is iixed at 46 to the pinion and is keyed to the flange 42 of the nut as indicated at 4l, the fiange being retained in the barrel by means of a lock ring 48. A re-entry spring -49 is provided between the rin-g 36 and the end of the barrel 45 for urging the nut 4I into initial engagement with the threads 3B, and an anti-drift spring 5l located between the ring 36 and the flange 42 of the nut normally maintains the nut and its associated parts in idle position.

According to the present invention longitudinal movement of the screw shaft 35 away from the engine gear is resisted by an elastically deformable member which is thereby placed in pure axial shear. As here shown this is accomplished by means of an outer barrel member 52 seated on the end of the power shaft 3| in abutting relation with the ends 53 of the splines 34 and clamped there-against by a nut 54 threaded on the end of the power shaft. An elastically deformable ring 55 has sleeves 56 and 51 bonded to its interior and exterior surfaces respectively, and these sleeves are arranged to seat on the end of the screw shaft 35 and the interior of the barrel 52 against a shoulder 58 on the screw shaft and a shoulder 5S in the barrel respectively.

In the operation of this embodiment of the invention rotation of the power shaft 3l is transmitted to the screw shaft 35 through the splines 34, thereby causing the nut 4l to be threaded along the screw shaft until the pinion 43 is moved into mesh with the engine gear 44 and against the stop shoulder 33. Further rotation of the screw shaft causes it to be moved away from the engine gear, thus applying a shearing force to the ring 55 until the resistance of the ring is built up sufficiently so that the resultant torque transmitted from the nut 4| through the barrel 45 to the pinion causes the pinion to rotate and crank the engine.

It will be appreciated that in all the embodiments of the invention illustrated, the capacity of the yielding connection for the transmission of force is large in comparison with the size of that member inasmuch as all parts of the member are placed simultaneously under stress, and the supercial areas transmitting such stress are large. The fact that in each case, the torque is transmitted through a positive mechanical connection under the control of the yielding shear member, also renders the torque capacity of the device large in comparison to the volume of the yielding member.

Although certain embodiments of the invention have been shown and described in detail, it will be understood that other embodiments are possible, and that changes may be made in the design and arrangement of the parts without departing from the spirit of the invention as defined in the claims appended hereto.

What is claimed is:

l. In an engine starter drive a pair of concentric spaced Cylinders, a cylinder of elastica-ily deformable material interiorly and exteriorly connected to said members respectively, torqueresponsive means for imparting relative axial movement to said members, and means preventing relative rotation between said members.

2. In an engine starter drive a power shaft, a pinion slidably journalled thereon for engagement with an engine member, means including inter-threaded members for traversing and rotating the pinion, said means including concentric cylindrical members positively connected for rotation in unison with freedom for relative longitudinal movement, and a ring of elastically deformable material having bonded connections interiorly and exteriorly to said concentric members respectively.

JAMES E. BUXTON.

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